Sealed potentiometer



Jan. 4, 1949. GORE 2,457,814

SEALED POTENTI OMETER Filed Aug. 9, 1946 IN V EN TOR. /ZV//V6 6050KPatented Jan. 4, 1949 UNITED STATES PATENT OFFICE SEALED POTENTIOMETERIrving Gordy, Eatontown, N. J. Application August 2 1946, Srial No.689,355

(Granted under the act of March 3, 1883, as amended April 30, 19.28; 3700. G. 757) 6 Claims.

The invention described herein may be manufactured and used by or forthe Government for governmental purposes without payment to me of anyroyalty thereon.

This invention relates to improvements in potentiometers, rheostats, andsimilar electrical resistance devices.

An essential object of this invention is to provide a potentiometer,rheostat, and the like, which is arranged and constructed so that allthe current carrying portions of the component are protected fromdeleterious effects produced by moisture, salt, dust and othersubstances of the atmosphere. I

A more particular object of this invention is to protect and seal theresistance strip with its current carrying wires in the casing by theuse of a thin metal diaphragm mounted between said strip and the openingon the casing, said diaphragm being provided with bellows so as to allowfor flexing of the diaphragm into engagement with the selected portionof the resistance strip and thereby complete the circuit through thedevice.

These and various other. objects and advantages are attained with thisinvention as will become apparent from the following description, takenin connection with the accompanying drawings wherein the invention isshown in its preferred form, it being evident that other arrangementsand forms of construction may be resorted to in carrying out the objectsand purposes of this invention.

In the drawings:

Fig. 1 is a central sectional view through the potentiometer. I

Fig. 2 is partly an end view and partly a sectional view, takensubstantially on line 2-2 of Fig. 1.

The drawings illustrate my invention applied to a resistance mechanismwhich is shown in the form of a potentiometer, and it may likewise beapplied to a rheostat and the like. The potentiometer as disclosedcomprises a casing 5 which is substantially cup-shaped, and it is closedat one end 6 and has an opening 1 at the other end, the casing beingconstructed of ceramic or glass or other suitable insulating material.Flange means 8 extends radially outward from the open end 1 of thecasing and is provided with apertures 9 for receiving fastening elementsl0 whereby to secure the mechanism on a panel II or the like. Theelements I!) are shown as securedthrough the flange 8 and the panel H,and through a 2 gasket l2 which is interposed between the flange and.the panel.

The resistance strip [6 provided herein is shown as including the wirecoil 11 wound upon a suit? able insulating member [8. Said member orstrip is in the form of a partial cylinder or partial ring providing twospaced end parts, and is mounted close to the cylindrical wall of thecasing, substantially as shown herein.

A sheet member or diaphragm 2| of metal, such as phosphor-bronze,berillium, copper, etc., is mounted in the casing between the opening 1and the resistance strip l6, and it is normally spaced from said strip.The diaphragm is substantially cylindrical or tubular in shape and ithas its outward end 22 sealed onto a ledge 23 on the casing, by means ofsolder 24 or the like to provide a hermetical seal. The inner end of thediaphragm is mounted to allow for yielding or flexing, and it istherefore provided with bellows 25, which are preferably formed integralwith said inner end of the diaphragm, and said bellows are securedsealed to the inner end 6 of the casing, by means of solder 26 or thelike. The resistance strip I6 is thus hermetically sealedin the casingbeneath said diaphragm 2| with its bellows 25.

An operating member is provided and includes a shaft 21 which extendsrotatably through a collar 28 mounted in said panel I I. From the innerend of the shaft extends radially an arm 29 having a rounded end portion30 which engages and is slidably movable over the cylindrical diaphragm2|, in such a manner as to depress the diaphragm into contact with theselected part of the resistance strip I6, thereby completing the circuitthrough the potentiometer and including the desired amount ofresistance. The arm 29 is preferably arranged in two spaced parts havinga spring 3| interposed therebetween, so as to constantly urge the end 30against the diaphragm to move the latter in contact with the resistancestrip; while the adjacent parts of said arm are each provided with astrap 32 operatively connected by bolts 33 extending through aperturesprovided in the two straps, so that these straps and the arm parts willbe urged yieldably apart to press the diaphragm against the strip.

A terminal post 35 extends through the end wall 6 of the insulatingcasing, being secured sealed therein, and it has a wire conductor 36connecting its inner end electrically with said bellows 25, while anelectric conductor 3'! is connectible to its outer end. In thepotentiometer, a pair of terminal posts 38 are likewise extended throughthe casing and sealed therein with solder or in some approved manner,said posts having their inner ends electrically connected by condoctors39 with the opposite ends of the resistance strip l6, while the outerends of these posts are connectible to electric conductors 40 in theusual manner. For the rheostat, one terminal post 38 only is used, beingelectrically connected to one end of the resistance strip.

I claim:

1. In a device of the class descirbed, a tubular casing closed at oneend with an opening in the opposite end thereof, a resistance stripmounted within the casing, a nonporous metallic tubular diaphragmmounted within the casing between the resistance strip and the openingand being normally closely spaced from said resistance strip, saiddiaphragm being secured at the outer end sealed to the casing, annularflexible sealing closure means formed at the inner end of the tubulardiaphragm and extending from said end in sealing engagement with theclosed end of the casing to protect and hermetically seal the resistancestrip within the casing between the diaphragm and the inner wall of thecasing, terminal posts extending through the casing wall and securedairtight therein, one post being electrically connected at its inner endwith said diaphragm and another post extending into the closed spacebetween the casing wall and the diaphragm and connected with saidresistance strip, and rotatable shaft operating means extendingcentrally of the diaphragm and concentrically of the casing having meansthereon to force a portion of the diaphragm into electrical contact witha selected part of the resistance strip to establish an electricalcircuit including the resistance strip in the circuit of the device fromsaid ter minal posts through said diaphragm and said re sistance strip.

2. In a device of the class described, a cylindrically shaped casingclosed at one end and having at the other end an opening and means formounting the casing in operative position, an electrical resistancestrip having current carrying means the shape of circular ring mountedconcentrically within the casing close to the cylindrical inner surfaceof the casing, a tubular shaped flexible metal nonporous contactdiaphragm mounted centrally to and normally spaced from said resistancestrip, said tubular diaphragm having its outer end sealed in the openend of the casing, yieldable nonporous sealing means provided at theother end of said tubular diaphragrm extending between the same and theinner end of the casing in sealing relation thereto, whereby that end issecurely sealed to the cas ing but is afforded yieldable movement towardthe resistance ring, said diaphragm and yieldable means hermetically thecurrent carrying means of the resistance strip within the casing, andelectrical terminal posts sealed in the casing, one of said postsextending from the exterior into the casing between the closed end andthe diaphragm yieldable sealing means with its inner end electricallyconnected to said resistance strip and another of said posts having itsinner end connected to said diaphragm, the outer ends of said postsbeing adapted for connection with electricity conducting means, andmovable operating means extending into the opening of the casingcentrally of said tubular diaphragm including resilient pressure meansbearingv on the diaphragm to force the portion contacted thereby intocontact with a selected part of said strip thereunder to close a circuitbetween said terminal posts end flanged outwardly and secured and sealedto the casing between the resistance strip and the opening, a nonporousbellows formed integrally on the other end of the diaphragm and sealed rto the closed end of the cylindrical casing to protect and hermeticallyseal the resistance strip in the casing between the diaphragm and thecasing wall, three terminal posts extending through the casing wall, twoof said posts extending into the sealed space between the tubulardiaphragm and said wall and sealed therein, an electrical connectionbetween the inner end of one of said posts and the diaphragm, andelectrical connections between the ends of the resistance strip and thesaid two posts, and movable means extending centrally into said casingincluding resilient pressure means slidable on the interior ofthetubular shaped diaphragm adjacent the bellows sealing portion toforce a portion of the diaphragm into electrical contact with a selectedpart of theresistance strip.

4. In a potentiometer and the like, a cupshaped cylindrical casing ofinsulating material closed at one end and open at its other end havingradial flange means at the open end whereby to mount the casing on asupport, a cylindrically curved electrical resistance strip mountedwithin the casing closely adjacent the inner wall thereof, asubstantially cylindrical diaphragm of electrically conductive materialmounted concentrically within the casing inwardly of said resistancestrip in closely spaced relation thereto, said diaphragm having its endadjacent the casing opening secured and sealed to the casing and havinga bellows portion formed at the other end extending concentrically intosealing relation with the closed end of the casing for mounting that endof the diaphragm flexibly to the casing, whereby to protect andhermetically seal the resistance strip within the casing between thediaphragm and the casing wall, terminal posts extending through thecasing wall between the casing and the diaphragm and sealed therein, andan electrical connection between one post at its inner end and saiddiaphragm, electrical connections between two of said posts at theirinner ends and the two ends of said resistance strip, and an operatingshaft concentrically extending into the casing opening having an armwith radial pressure means thereon movable upon said diaphragm to forcea portion thereof into electrical contact with said resistance strip.

5. In a hermetically sealed device of the class described, a cylindricalcasing closed at one end, and an impervious flexible resilientcylindrical electrical contact diaphragm member disposed concentricallywithin the cylindrical casing in spaced relation to the inner wallthereof said diaphragm member having its opposite ends secured to theinterior of the casing in hermetically sealed supporting relationthereto, to form an annular cylindrical hermetically sealed chamberwithin said casing, a cylindrically curved resistance stripconcentrically mounted within said casing within said hermeticallysealed chamber in closely spaced relation to the outer periphery of saidcylindrical electrical contact diaphragm, an electrical circuit terminalpost extending from the exterior of the easing into the interior of saidhermetically sealed chamber, an electrical connection within the saidhermetically sealed chamber between said terminal posts and one end ofthe resistance strip, a second terminal post extending into said casingand electrically connected to said flexible resilient cylindricalelectric contact diaphragm member, a rotatable operating shaft journaledconcentrically within said casing, radial pressure applying means fixedon said shaft in contact with the interior of said cylindrical contactdiaphragm intermediate its ends for forcing the contacted portion ofsaid cylindrical contact diaphragm into electrical contact with theportion of the contact strip thereunder, to establish an electricalresistance circuit within said hermetically sealed chamber between saidterminal posts through the inner resistance strip IRVING GORDY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,851,933 Schellenger Mar. 29,1932 2,007,462 Stoekle July 9, 1935 20 2,031,211 Dumke Feb. 18, 1936

